1. Field of the Invention
The invention relates to a frictional damper, in particular for spinner-type washing machines, comprising a tubular housing; a tappet guided displaceably in the housing and projecting over an end of the housing; articulation elements mounted on the free end of the housing and of the tappet; a damping housing, which is formed on the end of the housing on the tappet exit side and in which a friction lining is disposed, bearing with friction against the tappet.
2. Background Art
A frictional damper of the generic type is known from Spanish utility model 285 746, in which the tubular housing has an expanded receiving section in the vicinity of the end on the tappet exit side, which is closed toward the tappet side. The tappet is guided on the entire inside wall of the tubular housing. The tubular housing and/or the tappet have a vent in the vicinity of the respective free end. This frictional damper is very simple in structure; as a result of the way of guidance in combination with the way the damping lining is arranged, no defined frictional conditions can be attained. Furthermore, whistling occurs during operation.
It is known from EP 0 336 176 B1 to modify the mentioned frictional damper in such a way that the friction lining is disposed in a special damping housing, which is inserted into the tubular housing from the end on the tappet exit side, where it is fixed axially in the direction of its longitudinal axis. This makes the friction lining placed and held in a special damping housing a special aggregate which may vary in design for the generation of varying frictional conditions, but is insertable into an otherwise identical frictional damper.
A frictional damper for spinner-type washing machines is known from EP 0 407 755 B1, having a housing with a substantially circular cylindrical inside wall and a tappet which is displaceable coaxially in the housing, one end of which is extracted from the housing and the other end of which is provided with at least one damping piston. The damping piston is disposed on a bearing section of the tappet displaceably between spring elements that bear against stops. The spring elements may vary in length and adjustment, for retarded driving of differing friction linings to be obtained. This embodiment is to provide for amplitude-responding vibration damping, and for a soft transition in particular during the change of direction of the motion of the tappet relative to the housing. This is meant to make the system work with little noise.
U.S. Pat. No. 5,549,182 teaches to embody fictional dampers of the generic type as spring elements with prestressed compression springs. In this way it is ensured that the maintenance of a soft, quiet transition at the reversal points is accompanied with uniform damping over the full stroke in the case of high oscillation amplitudes and with substantial freedom from damping in the case of low oscillation amplitudes.